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Old 07-10-2004   #16
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Re: Optimax in a cinq

Quote Originally Posted by Bushboy
is it just me or is this stuff a load of arse?

i filled my cinq up with Optimax (which cost me about 8 quid more than it would with normal petrol) and noticed no difference in acceleration .. all that i did notice is that a full tank lasted me 3 days trips to work and back where as a full tank of normal unleaded has seen me for just shy of 2 weeks (where i eventually ran out at a set of lights...)

optimax hates cinqs
Everyone, optimax won't have any effect on Cinq or Sei as they don't have whatís called a Knock Sensor. The knock sensor in effect adjusts the timing according to what fuel you use thus giving a cleaner burn and more power.

The reason behind optimax is 2 fold.

1. It is supposed to clean your engine out with it's detergents but IMHO it is not worth it as it could have adverse effects in actually dislodging carbon deposits that maybe sealing things like piston rings so this may have the effect of actually lowering compression due to gases getting down the side of the piston via the newly cleaned rings.

2. The higher the octane the less likely it is to detonate, basically this means that if you are running silly amounts of boost in your engine via a turbo the petrol will be less likely to combust under these high boost pressures before the spark plugs combusted the mixture. Cars with turbos will generally have a knock sensor, the timing is adjusted via his via the Knock sensor which I suspect Chiq or Sei don't have as they are basic engines to burn the fuel more efficiently.

Hope I haven't made anyone suck eggs but optimax is a con for most cars TBH.


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Old 08-10-2004   #17
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Re: Optimax in a cinq

Quote Originally Posted by ChavyBoy
Everyone, optimax won't have any effect on Cinq or Sei as they don't have whatís called a Knock Sensor. The knock sensor in effect adjusts the timing according to what fuel you use thus giving a cleaner burn and more power.

Hope I haven't made anyone suck eggs but optimax is a con for most cars TBH.


Ivan
I know that theory sounds good, but I definitely get around 10% more MPG on Optimax, checked over more than a dozen different tankfuls against different fuels.
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Old 11-10-2004   #18
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Re: Optimax in a cinq

Quote Originally Posted by fixitagaintomorrow
I know that theory sounds good, but I definitely get around 10% more MPG on Optimax, checked over more than a dozen different tankfuls against different fuels.
It's not a theory though
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Old 11-10-2004   #19
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Re: Optimax in a cinq

yeah, but still - it works in my centos....

You're right about the lack of a knock sensor though.
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Old 11-10-2004   #20
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Re: Optimax in a cinq

Quote Originally Posted by fixitagaintomorrow
yeah, but still - it works in my centos....

You're right about the lack of a knock sensor though.
To gaurantee you got about 10% more mpg you need to run a scientific test, simply driving about isn't good enough as you might not speed as much or where your driving is less busy so your not caught in traffic so you use less petrol.
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Old 11-10-2004   #21
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Re: Optimax in a cinq

no, I'm sorry but I will have to disagree with you properly here. Whenever I fill up I always brim the tank, so there's gonna be an absolute minimum variation between how full it is. The trip counter always gets zeroed - I never use it for anything else anyway. Whenever I fill up it's usually at the 1/4 tank mark with the light on, so about 27 litres goes in each time. On the daily drive to work etc. the roads are always clear, the beauty of working silly hours, so the speeds are virtually the same every day. I'll get 40 - 41 mpg on supermarket unleaded, but 44-45 on Optimax. BP Ultimate doesn't have the same effect though.

On long runs, steady 80-85mph, I can get 47mpg on Supermarket stuff or 52 on Optimax.
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Old 11-10-2004   #22
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Re: Optimax in a cinq

There is no sense in disputing this you don't need a theory, Test it out in your own car and see if it makes a difference for you. Your driving style will be much more of a factor in MPG than any petrol differences

I'm a bit of a saddo that records the milage reading every time I fill up. I must say I have not noticed any difference in MPG using optimax in my cinq. My MPG varies from about 40 to 48 and there seems to be no corrolation between MPG and Sainsbury's or Shell Optimax but I havn't been rigourous in noting when its been in filled with optimax or other expensive fuel (I have guessed from the price paid which runs are with optimax). After Petes post I will check again for myself.

Pete, - Have you tried Shell unleaded compared to supermarket fuel, does this have any effect? - could just be poor supermarket fuel.

In my MR2 Turbo I dont notice any difference in mpg either but there is a significant increase in power,about 10 bhp at 7,000 rpm, and the 0-60 drops from 5.6s to 5.1s [the MR2 being an import is designed to run on 100RON as available in Japan] Again though there is no significant difference between Sainsbury's Superunleaded and Shell Optimax. (power and 0-60 times measured using a Dyno Plus road dyno).
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Old 11-10-2004   #23
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Re: Optimax in a cinq

I haven't tried Optimax yet. But Shell Unleaded treats my car better than Morrisons
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Old 12-10-2004   #24
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Re: Optimax in a cinq

Quote Originally Posted by mckcrich
There is no sense in disputing this you don't need a theory, Test it out in your own car and see if it makes a difference for you. Your driving style will be much more of a factor in MPG than any petrol differences
Yep exactly. You can compare petrol MPG's on the road as IT IS NOT ACCURATE enough.

fixitagaintomorrow you are entitled to your opinion but it don't work. The higher octane can't be used by the fiat engine so it won't make a blind bit of difference 98 ron or not. I think will agree to disagree on this one.
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Last edited by ChavyBoy; 12-10-2004 at 17:44.
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Old 12-10-2004   #25
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Re: Optimax in a cinq

Quote Originally Posted by ChavyBoy
fixitagaintomorrow you are entitled to your opinion
Oh goody.

Quote Originally Posted by ChavyBoy
but it don't work.
oh, maybe I'm not then.
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Old 12-10-2004   #26
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Re: Optimax in a cinq

calm down boys
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Old 12-10-2004   #27
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Re: Optimax in a cinq

ok, sorry. Tone of previous message wasn't pleasant, but shouldn't have bitten.

Better reply - Perhaps it works better on tuned and superchipped engines, maybe mine is on the point of detonation and Optimax lets the engine work to its full potential?
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Old 12-10-2004   #28
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Re: Optimax in a cinq

Mines better with optimax> but then anything is better than sainsbury's unleaded

It damages your bank account tho!
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Old 12-10-2004   #29
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Re: Optimax in a cinq

Quote Originally Posted by fixitagaintomorrow
ok, sorry. Tone of previous message wasn't pleasant, but shouldn't have bitten.

Better reply - Perhaps it works better on tuned and superchipped engines, maybe mine is on the point of detonation and Optimax lets the engine work to its full potential?
If you are running a turbo then it wil help to a point yes.

Are you running a turbo ?
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Old 12-10-2004   #30
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Re: Optimax in a cinq

petes running 1 turbo 1242 and 1 n/a 1242
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